The parents of a 17-year-old girl shot dead this week by Denver police while she was driving a stolen car have called for a U.S. Justice Department civil rights investigation into her death.

The teen’s parents, Jose Hernandez and Laura Rosales, said in a letter sent to U.S. Attorney John Walsh that Denver police have a history of conducting lengthy investigations that “serve only to exonerate its officers.”

“We believe that a federal investigation is the only way to uncover the truth because we have little confidence in the Denver Police Department’s ability to conduct a fair and timely investigation,” the letter said.

Denver Police Chief Robert White initially said the officers opened fire when the car Hernandez was driving struck one of the officers, fracturing his leg, but White has since said the officer may have been injured trying to avoid the car.

The Colorado Latino Forum, an advocacy group, joined the family on Friday in calling for a civil rights investigation.

A spokesman for Walsh would say only that the office is aware of the family’s letter.

A Denver Police Department spokeswoman said chief White has confidence in his department’s investigators and the district attorney’s office.

In a written statement, the organization said that Denver prosecutors have an “abysmal” record in charging officers accused of excessive use of force, and police have issued “victim-blaming” statements before all the facts are known in the case.

Jessica Hernandez, in an unrelated incident earlier this month, was charged with speeding, eluding police, driving under restraint and resisting arrest, an Adams County District Attorney’s Office spokeswoman, outside Denver, said on Friday.

All of the charges were dismissed on Friday because of Hernandez’s death, and a Colorado State Patrol spokesman, which was the arresting agency, declined to provide details of the incident.

Greene and Jordan are on administrative leave until the police department’s investigation is complete, which the Denver District Attorney’s Office said could take several weeks.